Xantia rear calipers

p20 · Post by **p20** » 31 Jan 2006, 22:15

I fitted new rear discs and pads to the xantia last week. Had a bit of bother with the allignment. The new discs run closer to the inboard half of the caliper than the outer half. The brakes are binding. After a week of running round they aren't much better. Have pushed the pads back again today, but they still bind. I did clean some of the corrosion off the calipers when i fitted the discs, but the local specialist has advised giving them a good clean up.

So what grade of sand paper/emery cloth would you recommend to clean the corrosion off?

Thanks in advance.

jeremy · Post by **jeremy** » 31 Jan 2006, 22:35

The main corrosion point is between the caliper and its mount on the trailing arm which suffers from galvanic corrosion. This can be considerable and can mean that the caliper won't sit on its mount properly. All this corrosion must be moved and it will be hard work - and probably need chipping away and filing to get it flat. If you use an angle grinder you risk doing some damage to the mount face.

The other place you can get corrosion is on the disc mount face on the hub. This must be flat - if its shiny without raided threads and the disc face is clean ou should be ok. Again if corrosion is severe you may have to file, otherwise emery cloth may do the job - but make sure there's no deposit in any of the bolt holes.

The disc should run approximately in the centre of the caliper if its set up properly. If its not is it possible you have vbeen supplied with the wrong discs. Have you got the old ones - if so it may be worth measuring and comparing.

p20 · Post by **p20** » 31 Jan 2006, 23:06

The discs were from Andyspares. Brembo, marked for all Xantia/Xm models. I chucked the old ones

Kowalski · Post by **Kowalski** » 01 Feb 2006, 10:44

The corrosion between caliper and suspension arm is a hard brittle material, it is quite easy to chip it off without damaging either the caliper or suspension arm surface. Those two surfaces should (in theory) be smooth and flat so if you use anything like a file or emery cloth you have to be very careful.

Personally, I used a steel scraper with a hard sharp edge (made from a piece of an inch wide hacksaw blade) and tapping the end of that was enough to make the corrosion chip away in large pieces. In my case the corrosion was over 1mm thick at one side tapering away to no thickness at the other.

When you've scraped / wire brushed both faces clean (without damaging them

a little bit of waterproof grease will keep the wet out and slow down the return of the corrosion. I don't know whether anybody has tried to paint the area, its probably a better idea than the grease but it'll be difficult to get paint to stick long term.

p20 · Post by **p20** » 01 Feb 2006, 16:57

Cleaned all the surfaces today using some sandpaper. Copperslipped the two faces between caliper and mount, it now works!!! Happy days

dexy350 · Post by **dexy350** » 04 Feb 2006, 21:20

well it looks like ive found a web site for Xantias ,well a decent one !
well i had the same problem today regarding the rear brakes .
After purchasing my 2nd xantia estate not to long back due to some nice old lady smashing my other one up .i thought i would just check the cars brakes on tuesday night now considering it passed an MOT in december and ive only done 300 miles in her you would think fine there shouldnt be any probs not until i removed the front wheels to find pads which were ney on down to the metal .
so of to the local guy who sells french car bits got some new pads for the front and the rear may as well do the lot while iam on new front pads in on wednesday .
today thought ill do the back ,well what a laugh, pads what pads !dics what dics these had more rust than the Lada .
the only shiney bit on one of the discs was where the caliper had been catching the disc .i thought this is strange and the pads what was left of them had been wearing at an angle .
Now having a good look round finaly spotted the problem whipped the caliper of cleaned the crap of .waited for the the wd to work trying to get the old discs of, sent wife for new discs.bit of heat works wonders as well .
wife comes back with new discs jobs a good en old discs off ,new ones on
puts the lot back together and hey presto we have working brakes .
Now i never trust garages and this car is a prime example full service History etc etc just been serviced yeah yeah and How the hell did it pass an MOT
There will be a few phone calls on Monday oh the joys of motoring
cheers

dnsey · Post by **dnsey** » 04 Feb 2006, 21:42

As a permanent solution to this problem, has anyone tried an insulating shim (mica springs to mind) between the faces?

AndersDK · Post by **AndersDK** » 04 Feb 2006, 22:05

The problem is water/salt ingress between the 2 alloy surfaces. It would do nicely to smear a layer of sticky body protector or alu paste on the cleaned surfaces to seal off the joint. Thats all whats needed.
Worked well on my CX rear arms which also are alloy.

BTW : If the rear calipers are replaced with s/h ones - any mismatch on distance to disc may be caused by wrong caliper types

This is because BX & CX rear calipers are exactly the same types - except for the offset to the discs. Donno why Citroen made this silly modification

BTW2 : Copper paste is no good on alu parts. Only to be used on steel surfaces. When you dismantle parts later you can see the copper contents make the alloy corrode black.

PS : If you need to grind the back of the caliper - then use a glass shelf - or any other thick and stable sheet of glass. Glass has a very smooth and perfect surface. Lay a sheet of emery paper grade 180 over the glass - and scrub the part back and forth. Works a treat.
Can be used to grind/clean down rear brake pads too - but use grade 60 instead.

26joenz · Post by **26joenz** » 05 Feb 2006, 21:38

Hi, i have replaced the brakes on a citroen xantia today, what a job, had to do both front and rear disks, unfortunately this broke the seal, i have blead all the air out but cannot get the brake pedal to rise up and now the rear suspension is taking forever to rise, does anyone know of a solution to this?

dnsey · Post by **dnsey** » 05 Feb 2006, 22:05

No need to double post

Please see my reply (and probably others in due course) in your other thread.

john alexander · Post by **john alexander** » 06 Feb 2006, 20:45

Hi I used an angle grinder, working on the basis that even if you do make it a bit rough It'll still be better than with the corrosion.regards john.

Kowalski · Post by **Kowalski** » 07 Feb 2006, 12:47

john alexander wrote:Hi I used an angle grinder, working on the basis that even if you do make it a bit rough It'll still be better than with the corrosion.regards john.

If you make it rough, you're leaving lots of nice pathways for water and dirt to get in to make the whole lot corrode again. You're also potentially asking the bolts to clamp two things in such a way that the bolts get bent, i.e. the two faces aren't flat and parallel any more.

davek-uk · Post by **davek-uk** » 08 Feb 2006, 09:18

My rear callipers were corroded so bad one of the securing bolts snapped! They were rubbing the disks pretty bad. I cleaned the area up and put hermatite blue (all I had) on the mating surfaces to prevent further corrosion. Some months later, at MoT time, I had to change the disks (damn he noticed). Removing the callipers, I noticed that the hermatite was pretty patchy. Putting them back together this time I placed thick plastic sheet between the calliper and arm – now there is no chance of metal to metal reaction. Admittedly I've yet to see if everything is still running true.

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Xantia rear calipers

Xantia rear calipers

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